JPH0345349A - Color printer - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a tone difference between a forward-printing surface and a reverse-printing surface by conducting a delivery amount correction for eliminating a tone difference resulting from the order of ink delivery different between the forward printing and the reverse printing. CONSTITUTION:Heads A - D are arranged in order along the reciprocating direction thereof, and each of the heads is provided with N pieces of ink delivery nozzles arranged at right angles to the reciprocating direction. On the other hand, recording paper P is fed in a direction of an arrow Y, and the respective delivery heads A - D reciprocate in a direction X at right angles to the feed direction Y of recording paper P. A color processing conversion part 11 applies a color correction to an original color signal 1 in accordance with the impurities of inks Y, M, C and conducts an under color removal, an India ink plate generation, and other adjustments. A multiplexer 12 distributively outputs a color processing converted color signal 3 for forward printing and a color processing converted color signal 4 for reverse printing. A tone difference correction part 13 provided with a tone difference correction table corrects the reverse-printing color processed color signal 4 and outputs tone difference corrected color signal 5. A head drive processing part 15 applies various types of processing to the color signals 3, 5 inputted therein.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color printer capable of reciprocating color printing, such as a flat scanning color printer.

Prior Art 3 - 7 Recently, flat scanning color printers have been increasingly used as output terminals for office automation equipment and video information equipment. This printer has a reciprocally movable ejection head that ejects ink both forward and backward, allowing for reciprocating color printing, so the printing speed is fast.

A specific method of reciprocating color printing is known, for example, in Japanese Patent Application Laid-open No. 75255/1983.

Hereinafter, two reciprocating color printing methods in a conventional flat scanning color printer will be described with reference to the drawings.

In the first reciprocating color printing method, as shown in FIG.
Magenta), c (c-cyan), D (BK-black)
It is equipped with four ink ejection heads. Each of these heads A, B, C, and D is mounted on a single carriage (not shown) and is movable back and forth, and each discharge head has N discharge nozzles. Recording paper (recording body) P is fed in the direction of arrow Y in the figure, while
The ejection head reciprocates in a direction X perpendicular to the feeding direction Y of the recording paper P.

In the past, the ejection head moved from left to right to eject ink, and as shown in FIG. 7, N947 color prints were made. When the color printing of the past is finished,
The recording paper is advanced by N lines, and then color printing is started at the time of return. When returning, the ink ejection operation is performed while the ejection nozzle moves from right to left, and as shown in FIG. 7, N947 color prints are made.

Next, the second reciprocating color printing method will be explained.

In the second color printing method, the spacing between the ejection nozzles in each head A to D is set to a pinch interval that is twice the print line pitch (1/2 the density), and in the past, the ejection head was moved from left to right. As shown in Figure 8, 1
Line spacing, that is, conventional 1. Color printing for N947 is performed at /2 density. When the previous color printing is completed, the recording paper P is fed by one line, and the backward color printing begins. When returning, move the ejection head 5 from the right,
- to the left, and as shown in FIG. 8, color printing is performed for the middle line N lives of the previous print.

Problem to be Solved by the Invention However, in the case of the first method, the overlapping order of the ink is reversed between the forward and backward printing, so there is a noticeable difference in tone between the printing surface of the forward printing and the printing surface of the backward printing. There is a problem that there is.

In the case of the second latter method, the forward print line and backward print line alternate line by line, so the difference in color tone between the printed side and the backward print side becomes less noticeable, but the prints printed with the same nozzle Since the lines run adjacent to each other in parallel, there is a problem in that quality deterioration due to variations in the amount of ink ejected between nozzles is doubled.

In view of these circumstances, this invention provides a reciprocating color printing method that eliminates color tone differences due to differences in the direction of gutter movement during forward and backward ejection without increasing quality deterioration due to variations in ink ejection amount. The objective is to provide a color printer for the color printer.

6 /\ Means for Solving the Problems In order to solve the above problems, the Noyler printer according to claims 1 to 4 includes a plurality of reciprocating ejection jets that eject ink corresponding to each of a plurality of colors. It is equipped with a signal supply means for supplying an ejection control signal to the head and these ejection heads to perform ink ejection operations both in the forward and backward directions, and at least one of the forward and backward ejection control signals is applied to the ink in the forward and backward operations. The apparatus also includes a color tone difference correcting means that performs discharge amount correction to eliminate color tone differences due to differences in discharge order.

In color printers, the original color signal is normally input, processed, and then supplied to the head as an ejection control signal. This may be done at any point after the color signal is input until it is applied to the head. In other words, it is only necessary that the ejection control signal finally given to the head incorporates ejection amount correction to eliminate the color tone difference.

A12 In the color printer according to claim 2, the color tone difference correction means further includes a color correction table according to the color tone difference between the print color at the time of return and the color at the time of printing, and based on the table. Ejection amount correction is performed in the return signal system to eliminate color tone differences.

In the color printer according to claim 3, the color tone difference correction means further includes a color correction table according to the tone difference between the previous print color and the previous print color, and the color tone difference correction means adjusts the previous signal based on the table. The system performs discharge amount correction to eliminate color tone differences.

In the color printer according to claim 4, the color tone difference correcting means further includes a color correction table according to the tone difference between the print colors of the past and a predetermined reference color, and the color tone difference correction means is further provided with a color correction table according to the tone difference of the print color of the past with respect to a predetermined reference color, and the color tone difference correction means is further provided with a color correction table according to the tone difference of the print color of the past with respect to a predetermined reference color. In addition to applying a discharge amount correction to eliminate the difference, it also has a color correction table according to the difference between the predetermined reference JY back of the print color at the time of return. The signal system performs ejection amount correction to eliminate color tone differences.

Function: In the color printer of the present invention, at least one of the ejection control signals supplied to the ejection head incorporates an ejection amount correction that eliminates the difference in color tone caused by the difference in the order of ink ejection between the forward and backward times. Therefore, the difference in tone between the previous print image and the previous print image is eliminated.

Moreover, since there is no need to intertwine the previous print lines and the return print lines, there are no adjacent print lines from the same nozzle, which can accentuate variations in the amount of ink ejected from the nozzles and degrade quality. It doesn't happen.

Embodiment Hereinafter, a color printer according to the present invention will be explained in detail based on an embodiment thereof.

Embodiment 1 FIG. 1 shows the configuration of a flat scanning color printer according to Embodiment 1 according to the signal flow.

9,-.

As shown in FIG. 6, the printer fields 16 are A (yellow), B (magenta), and C (cyan).

It is equipped with four D (black) discharge ports, and each head A to D is mounted on one carriage (not shown) and can move back and forth. These heads A
-D are arranged in order along the reciprocating direction (main scanning direction), and N are arranged in a direction perpendicular to the reciprocating direction, respectively.
It has several ink ejection nozzles. On the other hand, the recording paper (recording body) P is sent in the direction of the arrow Y in the figure, and is sent to each ejection y)'
A to D reciprocate in a direction X perpendicular to (crossing) the feeding direction Y of the recording paper P.

1 is an original color signal (original color signal) containing information to be printed on recording paper P, and each pixel is divided into Y (yellow), M (magenta), and C (cyan) color components. It has been disassembled. Reference numeral 11 denotes a color processing conversion unit, which performs color correction on the original color signal 1 according to Y, M, and C ink impurities, and makes adjustments such as UCJI, (undercolor removal), and black plate generation. .

2 is a color signal of the color processing converter. 14 is 10
,, This is a printer mechanical control unit (mechanical system control unit), and has functions such as basic black y generation for flint control, head movement control, recording paper feeding control, etc. 7 is a forward/return signal, in which the head is at the home position (here, the recording paper P
When the case of moving from the left end of the line to the opposite side is called the forward time, and the case of moving in the opposite direction is called the return time, the forward/return signal is the control signal that controls the forward time or the return time. 8 is a control signal such as a clock. 12 is a multiplexer;
A color processing-converted color signal 3 for previous printing and a color processing-converted color signal 4 for backward printing are respectively output. Reference numeral 13 denotes a tone difference correction section (tone difference correction means), which has a tone difference correction table to be described later, and corrects the reproduction color processing source color signal 4;
The color signal 5 of the tone difference correction section is output. A head drive processing section 15 performs various processing on the input color signals 3.6. The head drive processing unit 15 performs processing such as storage and readout into the line buffer memory, signal delay, ejection correction, pulse width modulation, and high voltage amplification, depending on the plane scanning method, head configuration, characteristics, etc. It is.

Next, the color correction table of the tone difference correction section 130 will be explained. FIG. 4 shows the configuration for each block when creating a color correction table.

31 is a color batch from the past (single color and mixed colors with different tones) made only from the past prints, and the first
It was created by inputting the original color signal for color batch into the color printer shown in the figure and switching the multiplexer 12 to exclusive use for the past. Reference numeral 32 is a restored color batch (one in which gradations are created using a single color and a mixed color) that is produced only by reprint printing.The original color signal for the color batch is input to the color printer of Embodiment 1, and the multiplexer 12 is used exclusively for reprinting. and the color tone difference correction section 13
It was created without making any corrections.

33 is a color scanner, which has the function of separating colors into R, G, and B, measuring the density, converting the results to Y, M, and C, and outputting them, as well as having a built-in memory and color scanner. It also has a function of storing information (scanner signals) after scanning batches 31 and 32. 34 is a scanner signal of the color patch 31 in the past, and 36 is a scanner signal of the color patch 32 in the return. 36 is
This is a color tone difference correction table creation unit that compares one of two human input signals (for example, two scanner signals) with the other signal, and calculates the color in equation (1) below using the method of least squares, etc. It has a function to calculate correction coefficients and create a color correction table.

(X)=(A)(Y) ・・・・・・(
1) Continuing to 13, the creation of a tone difference correction table and the reciprocating color printing operation in the color printer of the first embodiment will be specifically explained.

As described above, color patches 31 and 32 are first created, respectively. These color patches 31 and 32 are read by a color scanner 33, and the signals are stored in a built-in memory. The respective scanner signals 34 and 35 are simultaneously sent to the tone difference correction table creation section 36 in synchronization with the next reading clock. Color tone difference correction table creation section 3
6 is the scanner signal 3 of the Zyler panochi 32 at the time of return, based on the scanner signal 34 of the color patch 31 from before.
6 is compared, a tone difference correction coefficient A is calculated, arranged in the form of a table, and created as a tone difference correction table 37 built in a memory element. This color tone difference correction full 37 is stored inside the color tone difference correction section 13.

On the other hand, in a color printer, the original color signal 1 is 14 Y, M, C! The signal is input to the color processing converter 11 in the separated form into colors, the above-mentioned processing is performed, and the color signal 2 is output to the multiplexer 12. The multiplexer 12 outputs a forward color signal 3 and a backward color signal 4 in accordance with the forward/return signal 7 from the printer mechanical control section 14 .

For example, when the head 16 is in the current state, the multiplexer 12 is switched to the previous state, and the output color signal 3 is sent to the head drive processing section 16 and stored in the line buffer memory. When the head 16 begins to advance in the previous direction and passes a print start point (not shown), the color signals 3 stored in the previous line buffer memory are taken out in the order in which they were input. After this signal 3 is processed in real time by the head drive processing unit, processing necessary for head drive such as signal delay, ejection correction, pulse modulation, and high pressure amplification is performed according to the plane scanning method, head configuration, and characteristics. , a discharge control signal 6 is sent to the nozzle in the head 16.
It was supplied as a paper and printed in the past.

15 heh.

On the other hand, when the head 16 advances and the forward printing is completed, the multiplexer 12 which has finished sending out the color signal 3 is switched to the backward printing and outputs the color signal 4 to the tone difference correction section 13. In addition, due to the end of previous printing, the recording paper P is N.
The unprinted area is fed by the amount of 917 minutes, and the unprinted area is
It comes to be.

As described above, the tone difference correction section 13 has the tone difference correction table 37, and performs correction (correction conversion) on the input color signal 4 based on the tone difference correction table 37.

The corrected color signal 6 is sent to the head drive processing section 16 and stored in a line buffer memory for restoration.

When the head 16 reverses during the return and passes the print start point (not shown) on the return side, the color signals 6 stored in the line buffer memory for the return are input in the reverse order of input ( i.e. from the last signal on the line). In response to this signal 6, the head drive processing unit 15 performs processing necessary for the henode drive, such as signal delay, ejection correction, pulse modulation, and high-pressure amplification, in real time, depending on the planar scanning method, head configuration, and characteristics. After that, the ejection control signal 6 is supplied to the nozzles in the head 16, and a return print is performed.

As is clear from the above explanation, in the first embodiment, the color patch 31 at the time of return is used as the reference for the color patch 31 of the past.
2 and obtains a tone difference correction table, and based on this, ink ejection from the nozzles is controlled so that the tone of the previous print matches the tone of the previous print. Therefore,
The color tone of the previous print surface and the return print surface becomes uniform, improving quality. Furthermore, since print lines produced by the same ejection nozzle are not adjacent to each other, there is no quality deterioration due to accentuated ejection amount variations.

Embodiment 2 In Embodiment 1, in order to match the color tone of the backward print to the color tone of the previous print, a correction table was obtained based on the previous color patch 31, and correction was performed in the signal system on the backward side. , the color tone of the previous print may be set to 1 to match the color tone of the previous print. In FIG. 4, using the scanner signal 36 of the color patch 32 as a reference signal, the scanner signal 34 of the color patch 31 is compared to create a tone difference correction table, and as shown in FIG. In this way, the signal is input into the signal system on the former side. The other configurations and operations are basically the same as in the first embodiment, so their explanation will be omitted.

Embodiment 3 FIG. 3 shows the configuration of a flat scanning color printer according to Embodiment 3 according to the signal flow.

In the color printer of Embodiment 3, an independent color tone difference correction section is not provided, and as shown in FIG. This embodiment is basically different from the color printer of the first embodiment in that the two signal systems are respectively input into the signal system, and the color tone difference correction table is set as shown below.Other points are similar to the first embodiment.

First, creation of the tone difference correction table will be explained with reference to FIG. 5.

18 ・＼-/ 41 is a color patch based only on the past printing, and the original color signal for the color patch is input to the color printer shown in FIG. It was created without. Reference numeral 42 indicates a reprinted color patch by reprinting only, in which the original color signal for color punching is input to the color printer shown in FIG. 3, and the multiplexer 12
This image was created by switching the image to be used exclusively for restoration and without performing any correction by the brownish correction processing converter 19.

33 is a color scanner, which is the same scanner as in the case of FIG. 44 is a color patch scanner signal. 46 is a color patch original signal (reference color) created by the color patch 6o for the reference color.
It is.

Reference numeral 46 denotes a color tone difference correction table creation unit, which creates a color correction table 49 that includes not only color tone difference correction based on the difference between forward and backward times, but also color correction using ink, UC adjustment, and black plate adjustment. can be created. 4A is UC
R amount finger/toe designation signal, 19 ・＼U c Specifies the degree of R adjustment. 48 is a black signal amount designation signal that designates the degree of black (black) adjustment.

Table creation is done as follows.

The created color patches 41 and 42 are sent to the color scanner 33.
The signal is read and stored in the built-in memory. Color batch original signal 45 and old scanner signal 44
is input to the color tone difference correction table creation section 46 while being synchronized with the readout clock. At the same time, a UC density designation signal 47 and a black signal amount designation signal 48 are also input.

The color tone difference correction table creation unit 46 compares the previous scanner signal 44 with the color patch original signal 46 as a reference, calculates each thread count, arranges it into a table, and stores it in the memory element as a color correction table 49. Create in shape. This color correction color 49 is stored inside the color correction processing conversion section 18. A return color correction table stored inside the color correction processing converter 19 is also created in the same manner. Of course, in this case, the color batch 42 is used as the scanner signal.

On the other hand, in a color printer, the original color signal 1 input to the multiplexer 12 is converted into a forward color signal 3' and a reverse color signal 3' and a backward color signal according to the forward/return signal 7 from the printer mechanical control section 14. The allocation is output to 4.

While the head 16 is on the backward print side, the multiplexer 12 is switched to the forward print side, and the signal 23 processed by the forward color correction processing conversion section 18 is sent to the head drive processing section 16; While the multiplexer 12 is on the forward printing side, the multiplexer 12 is switched to the backward printing side, and the signal 24 processed by the backward color correction processing conversion section 19 is sent to the head drive processing section 15. After the respective signals 23 and 24 are processed in the same manner as in the first embodiment, they are supplied to the gutter 16 as ejection control signals 6', and forward printing and backward printing are respectively performed. It goes without saying that the recording paper P is fed by N lines between forward printing and backward printing.

It goes without saying that the color printer of the third embodiment also performs high-quality color prints like the color printer of the first embodiment.

Effects of the Invention In the color printer of the present invention, at least one of the forward and backward ejection control signals supplied to the ejection head includes an ejection amount correction that eliminates the difference in color tone due to the difference in the order of ink ejection between the forward and backward times. Therefore, there is no difference in tone between the previously printed surface and the backward printed surface. Furthermore, since lines printed by the same nozzle are not adjacent to each other, there is no possibility that variations in the amount of ink ejected from the nozzles are accentuated and the quality deteriorates. In other words, excellent quality two-way color printing can be performed.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are block diagrams showing the main components of a color printer according to an embodiment of this thin film, and FIG. 4 is a block diagram of the color printer shown in FIGS. 1 and 2. FIG. 6 is a block diagram showing the configuration for creating a tone difference correction table in the color printer shown in FIG. 3. Fig. 6 is a schematic explanatory diagram of the configuration around the ejection head of a flat scanning color printer, Fig. 7 is an explanatory diagram of the reciprocating color printing method of a conventional color printer, and Fig. 8 is an explanatory diagram of the conventional color printer. FIG. 7 is an explanatory diagram of a reciprocating color printing method of another color printer. 1... Original color signal, 6... Ejection control signal, 13.
17...Tone difference correction section (tone difference correction means), 16...
Head, 18.19...Color correction processing unit (color tone difference correction means), 31.41...Color patch from the past, 32.
42...Return color batch, 37.47...Tone difference correction chifur.

Claims (4)

[Claims] (1) Equipped with a plurality of reciprocating ejection heads that eject ink corresponding to each of a plurality of colors and a signal supply means for giving an ejection control signal to these ejection heads so that they perform ink ejection operations both in forward and backward directions. and a color tone difference correction means for correcting at least one of the forward and backward ejection control signals to eliminate a tone difference due to a difference in ink ejection order between the forward and backward times. printer. (2) The color tone difference correction means has a color correction table according to the color tone difference between the print color at the time of return and the print color at the time of the previous time, and the color tone difference is eliminated by the return signal system based on the color correction table. Claim 1: Correction of the discharge amount is performed.
Color printer as described. (3) The color tone difference correction means has a color correction table according to the color tone difference between the previous print color and the previous print color, and eliminates the color tone difference in the previous signal system based on the color correction table. Claim 1: Correction of discharge amount is performed.
Color printer as described. (4) The color tone difference correction means has a color correction table according to the color tone difference of the previous print color with respect to a predetermined reference color, and the ejection amount correction uses the color correction table to eliminate the color tone difference in the previous signal system. In addition, it has a color correction table according to the difference between the print color at the time of return and a predetermined reference color, and the ejection amount correction to eliminate the color tone difference in the signal system at the time of return is performed using the color correction table. 2. The color printer according to claim 1, wherein the color printer is